Vibration device fails to boost women's bone mass

NEW YORK (Reuters Health) - Although they are touted as a way to make bones stronger, whole-body vibration devices may not help older women hang on to their bone mass, a study out Monday suggests.

Canadian researchers found that of 200 postmenopausal women with low bone mass, those given a whole-body vibration device to use at home for a year showed no clear benefits.

The bottom line, the researchers say, is that the tactic cannot be recommended as a way for older women to stave off the bone-thinning disease osteoporosis.

"We found that a year of this therapy did not really increase bone density in postmenopausal women," said senior researcher Dr. Angela M. Cheung, of Toronto General Hospital.

If women want to preserve their bone mass, she told Reuters Health, it's best to stick with the tried-and-true: getting enough calcium and vitamin D in your diet, as well as regular, moderate exercise like walking and light weight training.

Cheung and her colleagues report their findings in the Annals of Internal Medicine.

Whole-body vibration devices consist of a platform, about twice the size of a bathroom scale, that sends mild vibratory impulses through the feet and into the rest of the body of a user standing on it.

The devices -- which can be bought online, for anywhere from about $200 to more than $3,000 -- are marketed as a way to improve muscle power, jump higher and sprint faster.

They are also advertised as tools for boosting bone mass, though doctors do not generally recommend them for preventing osteoporosis, according to Cheung.

There has been animal research suggesting that low-magnitude vibration boosts bone mass, Cheung noted. One theory is that those impulses mimic the effects of moderate exercise on bone, but do it more efficiently.

But studies of postmenopausal women -- who account for most cases of osteoporosis -- have had mixed results. Most of those studies have been very small, and usually failed to control for calcium and vitamin D use, which are key nutrients in preserving bone density.

So for this latest study, Cheung's team recruited 202 healthy postmenopausal women, most in their 50s and 60s, who had low bone mass, but had not yet developed osteoporosis.

All of the women were given calcium and vitamin D. Two-thirds of the group also received whole-body vibration platforms to use at home.

The devices were all low-magnitude, delivering mild vibratory pulses. Half of the machines were set at a relatively higher frequency (90 Hz), and half at a lower frequency (30 Hz). In both cases, the women were told to use the device every day for 20 minutes.

After a year, Cheung's team found no significant differences in bone mass between women who used the whole-body vibration devices and those who stuck with calcium and vitamin D alone.

On average, women in all three groups showed small bone-mass losses in most areas the researchers measured, including the hips, spine and shinbone.

Whole-body vibration is currently under study for preserving or boosting bone mass in other groups of people -- including teenagers, nursing home patients and people with spinal cord injuries.

"We can't say anything about whether it might work for those groups because we didn't study them," Cheung said.

Her team's study has other limitations as well. One is that the women used the devices at home, so the researchers don't know if they were used properly. Based on data stored in the machines, a significant minority of the women did not use the devices every day for the prescribed amount of time each day.

Still, Cheung said, the findings offer no evidence that whole-body vibration does thwart postmenopausal bone loss, and that's what women should keep in mind.